Laser device and method

ABSTRACT

A laser beam combining and power scaling device and method. A first highly reflective mirror residing perpendicular to the first optical axis reflecting radiation emitted from the first laser head. A first Q-switch in alignment with the first optical axis interposed between the first highly reflective mirror and the first laser head. A second highly reflective mirror residing perpendicular to the second optical axis reflecting radiation emitted from the second laser head. The second Q-switch in alignment with the second optical axis is interposed between the second highly reflective mirror and the first laser head. A third optical axis is coincident with the first optical axis. A third highly reflective mirror residing perpendicular to the third optical axis in alignment therewith. The third optical axis may include a third diode pumped laser head and Q-switch. A beam splitter resides at the intersection of the axes.

FIELD OF THE INVENTION

The invention is in the field of producing and transmitting laser beamsranging from high energy, stacked pulses having low frequency to lowenergy, sequenced pulses having high frequency. The invention includeslasers which are continuously pumped with light emitting diodes, laserswhich are continuously lamp pumped and lasers which are current pulsed.In the instance of current pulsed lasers when the frequency of thepulsations are sufficiently high, a pseudo continuous wave may beproduced. LASER is an acronym of Light Amplification by StimulatedEmission of Radiation. Laser radiation includes wavelengths which extendsubstantially from the infrared to the ultraviolet range.

BACKGROUND OF THE INVENTION

U.S. Pat. No. 5,307,369 to Kimberlin, one of the applicants in theinstant patent application, discloses in the abstract thereof: “A systemfor combining a plurality of laser beams into a combined output beamfrom at least two laser sources includes the removal of conventionalperpendicularly oriented output windows from each of the laser sources.Reflecting mirrors are positioned perpendicular to the optical axis atthe rear of the two laser sources. A fully reflecting mirror ispositioned perpendicular to the optical axis of the first laser sourceto reflect coherent light received from the first laser source. A beamsplitter is positioned between the first laser source and the fullyreflecting mirror at the intersection of the optical axes of the firstand second laser source. The beam splitter directs a portion of receivedcoherent light into a combined output beam, with the remainder beingdirected back to the first and second laser sources.”

Referring to FIG. 4 of the instant patent application (a reproduction ofFIG. 1 of the '369 Kimberlin patent specification, referred to byreference numeral 400 herein), and col. 4, line 47 to col. 5, line 64,it is stated that:

“In operation, laser output (represented by line 50) is produced bysustained resonant oscillation of coherent light through the lasersources 20 and 22, as controlled by multiple reflections off mirrors 30,32, 36, and beam splitter 40. These coherent light reflections arerepresented by lines 51, 52, 55, and 56, which are intended to representcoherent light traveling in both directions along the lines. Laser beamcombination proceeds, for example, by simultaneously pumping the activemedium of laser sources 20 and 22 with flash lamps (not shown). A photonleaving the laser source 20 can be randomly directed, for example,toward the first reflecting mirror 30. This photon (shown as line 51) isreflected from the mirror 30, and reverses its direction to move backinto the laser source 20. Here the photon encounters an active atom atan upper energy, which it stimulates to emit another photon of identicalfrequency, polarization, and direction. The pair of coherent photonsrespectively-encounter additional active atoms in the active medium tocreate still more coherent photons. The coherent photons eventuallyleave the laser source 20 to pass toward the beam splitter 40. When thecoherent photons encounter the beam splitter 40, about 50% are reflectedto provide output beam 50. The remainder pass through splitter 40 andproceed (line 54) to be reflected backwards from fully reflective mirror36 towards the beam splitter 40. Again, about 50% of the coherentphotons are reflected, but this time they are directed toward the lasersource 22. The remaining coherent photons proceed (line 53) back towardlaser source 20. These coherent photons pass through the laser source 20to create still more coherent photons, which exit the laser amplifierfor reflection from the mirror 30. This positive feedback process ismultiply repeated to create substantial numbers of coherent photons, atleast until the number of active atoms in the active medium drops belowsubstainable (sic, “sustainable”) lasing threshold. A certain percentageof coherent photons directed toward the laser source 22 by reflectionfrom beam splitter 40 also eventually proceed back along line 52 tosustain coherent photon production, similar to that previously describedfor those coherent photons that travel from line 54 through beamsplitter 40 and along lines 53, 52. The coherent photons reflected (line55) by beam splitter 40 toward laser source 22 pass into the lasersource to trigger a coherent photon cascade similar to that described inconnection with laser amplifier 20. The coherent photons leave the lasersource 22 (line 56), are reflected back into the laser source 22 totrigger production of still more coherent photons. These photons leave(line 55) the laser source directed toward the beam splitter 40. About50% of the coherent photons pass through the beam splitter 40 arecombined with coherent photons arriving from the laser source 20 (lines52 and 53). The remaining coherent photons are directed (line 54) towardmirror 36, which as previously described reflects the coherent photonstoward the beam splitter 40. The process of coherent photon production,with some coherent photons passing through the beam splitter 40 towardlaser source 20, and the remaining coherent photons being directed backto laser source 22, is again repeated. Although the exact energy of thecombined output beam 50 depends upon the active medium employed,scattering and absorption losses, time and energy of pumping action, andother factors known to those skilled in the art, typically two 400 wattlaser sources can be combined as described to produce about 800 watts oflaser output with minimal degradation in beam diameter and focus ascompared to a 400 watt laser amplifier alone. As will be appreciated bythose skilled in the art, pulsed operation is not required for operationof the described embodiment. Low power continuous laser amplifiers canalso be combined to double the power of the output beam. In addition,the system 10 as shown in FIG. 1 can also be operated to increaserepetition of laser pulses. Instead of simultaneously pumping the lasersources 20 and 22, the laser sources 20 and 22 are alternately pumped,providing a series of laser beams directed along the same optical axis.In this mode, losses due to absorption and scattering in the non-active,“cold” laser source are slightly increased, but the repetition rate ofthe system can be doubled as compared to a single laser amplifier, whilestill delivering full rated power.”

The '369 patent to Kimberlin employed a lamp pumping system whichproduced combined and/or sequenced laser pulses. Two systems sold byElectrox, assignee of the '369 Kimberlin patent, employed a third laserhead (laser source) disposed in line 54 of FIG. 1 of the '369 patent toKimberlin.

A standard laser system 100 illustrated in FIG. 1 comprises a gainmedium 101 with a highly reflective rear mirror 103 and a partiallyreflective output coupler 102 through which the output beam 106 exits.Reference numerals 104, 105 and 106 represent the output axis.

Two current methods for power scaling of laser systems include multipleintra-cavity oscillators as illustrated in FIG. 2 and a MOPA system(Master Oscillator/Power Amplifier) as illustrated in FIG. 3. Themultiple intra-cavity oscillator method 200 combines multiple gainmediums 101, 201 between the highly reflective mirror 103 and thepartially reflective mirror/50% output coupler 203. Reference numeral202 represents the optical axes and the output of the second laser head201. The laser output after the coupler is represented by referencenumeral 204.

The MOPA system 300 illustrated in FIG. 3 uses a typically low poweroscillator (such as laser head 101) which seeds a second laser 301 via apartially reflective output coupler 302. Reference numeral 303represents the optical axis and reference numeral 304 represents thelaser output.

There are major disadvantages encountered with both of these methods.One of the main disadvantages is that as power is scaled up, some or allof the laser heads have all the laser power being transmitted throughthem. This causes increased stress and heating on the opticalcomponents, substantially lowers the quality of the laser beam, createslensing and optical waists that shift throughout the system, andseverely limits the power scaling achievable. A second majordisadvantage is that under both of these methods, the individual laserscannot lase efficiently independently.

Long pulse width (duration) at high power levels are problematic in thatthey cause recast layers, heat affected zones, micro-cracking anddelamination of materials. Therefore, it is necessary to accuratelycontrol the pulse width(s), stacking, sequencing and power of laserbeams.

SUMMARY OF THE INVENTION

Continuous wave lasers produce a steady beam at an essentially constantpower output. Pulsed lasers emit their energy in short duration bursts.

In the current pulsed laser disclosed and claimed herein, the multilaser head configuration provides an adjustable output ranging from highenergy, power stacked pulses at low frequency to low energy, sequencedpulses at very high frequency or any permutation of these parameters.When the current pulsed multi-lasers are operated at a sufficiently highfrequency of operation, the pulsed output is increased yieldingcharacteristics of a continuous wave (pseudo continuous wave). Most userapplications of lasers, for example, in the semiconductor andphotovoltaic end user applications, are driven by high throughput (rapidand efficient) manufacturing requirements.

The device and method disclosed herein yields a very flexible high powerlaser which enables control of the energy (Joules, J), average power(Joules/second, Watts) and pulse width (nano or micro-seconds).Q-switched systems are operated such that the optical output pulses arein nanoseconds. Current pulsed systems are operated such that theoptical output pulses are in microseconds.

The laser heads are preferably diode pumped, are energized 100% of theoperational time, and are controlled by Q-switches. This is known ascontinuous wave Q-switched operation. Multiple heads may be firedsynchronously (simultaneously), sequentially, or sequentially with timegaps between firings. The Q-switches may be operated to yield an outputcombining the outputs of the individual laser heads.

Pseudo continuous wave (CW) is only possible when the multiple laserheads are current pulsed. If the firing repetition rate is high enoughthen a pseudo continuous wave is produced from the multiple heads.

The multiple laser heads may alternatively be controlled by currentpulsing the laser heads. Current pulsing of an individual pulsed lasersystem is limited in the maximum duty cycle attainable depending on thesystem. In the disclosure made herein, the system is not limited by theduty cycle as the outputs of the laser heads may be combined. The dutycycle is equal to the ratio of the pulse duration divided by the pulserepetition time (pulse cycle length or time).

The innovative laser optics design combined disclosed herein togetherwith an industrial-grade power supply results in an extraordinarilyreliable and rugged diode-pumped Nd:YAG laser for industrial use.Efficient diode optical pumping is employed for improved performance andreliability. Optical beams are combined using two, three or more diodepumped heads. Q-switched pulse stability is less than 3.5% RMS up tooperational frequencies of 15 kHz. Q-switches are water cooledacousto-optical switches. The laser is operated at a wavelength of 1064nm in the multimode transverse mode. The nominal beam waist diameter is3.7 mm with a full angle nominal beam divergence of 12 mr(milliradians). Polarization is random. The frame of the power stationis 84 cm high, 60 cm wide and 85 cm deep. Optical rail length isstandard 26 cm high, 107 cm long and 56 cm wide. Recommended powersupply is 220 VAC, 3-phase, 50-60 Hz at 40 amps.

The specifications set forth above are by way of example only.Wavelength, rod size, beam diameter, polarization may vary. Multiplewavelengths, for example, infrared at 1064 nm, green at 532 nm, andultraviolet at 355 nm, as well as others may be used. Lamp-pumped ordiode-pumped systems may be used. Various beam sizes and divergencelevels may be employed. The lasers may be continuously energized withthe optical output being Q-switched.

The lasers may, alternatively, be current pulsed. Current pulsing ofmultiple laser heads with sufficiently high frequency yields a pseudocontinuous wave optical output. Q-switching yields short pulse durationsand cannot provide pseudo continuous wave output because the number ofheads necessary would be excessive to produce a pseudo continuous waveoutput.

A first example of the laser beam combining and power scaling device isdisclosed and claimed. The device includes first, second and third NdYAGlaser heads. The invention is applicable to other types of laser mediumsincluding gas. The first laser head has a first optical axis and isdiode pumped. A first highly reflective mirror resides perpendicular tothe first optical axis in alignment therewith behind the first laserhead reflects radiation when emitted from the first laser head. Thesecond laser head has a second optical axis and is diode pumped. Asecond highly reflective mirror resides perpendicular to the secondoptical axis in alignment therewith behind the second laser headreflects radiation when emitted from the second laser head.

The third laser head has a third optical axis and is diode pumped. Athird highly reflective mirror resides perpendicular to the thirdoptical axis in alignment therewith behind the third laser head. Thefirst and third optical axes are coincident. The second optical axisperpendicularly intersects the first and the third optical axes. A beamsplitter resides at the intersection of the second optical axis and thefirst and third optical axes. The laser output has a laser output axiscoincident with the second optical axis.

The first laser head emits radiation along the first axis into andthrough the beam splitter, the beam splitter directing a first portionof the radiation emitted from the first laser head into the third laserhead along the third optical axis. The beam splitter directs a secondportion of the radiation emitted from the first laser head along thelaser output axis coincident with the second optical axis.

The third laser head emits radiation along the third axis into andthrough the beam splitter. The beam splitter directs a first portion ofthe radiation emitted from the third laser head into the first laserhead along the first optical axis and the beam splitter directs a secondportion of the radiation emitted from the third laser head along thesecond optical axis into the second laser head.

The second laser head emits radiation along the second axis into andthrough the beam splitter, the beam splitter directs a first portion ofthe radiation emitted from the second laser head along the laser outputaxis. The beam splitter directs a second portion of the radiationemitted from said second laser head along the third optical axis andinto the third laser head. The laser output emits radiation from thefirst, second and third laser heads along the laser output axis.

A first Q-switch is positioned in alignment with the first optical axisbetween the first highly reflective mirror and the first laser head. Asecond Q-switch is positioned in alignment with the second optical axisbetween the second highly reflective mirror and the second laser head. Athird Q-switch is positioned in alignment with the third optical axisbetween the third highly reflective mirror and the third laser head. Thefirst, second and third Q-switches are vertical Q-switches which divertthe laser beam (radiation) vertically.

A fourth Q-switch is positioned in alignment with the first optical axisbetween the first highly reflective mirror and the first laser head. Afifth Q-switch is positioned in alignment with the second optical axisbetween the second highly reflective mirror and the second laser head. Asixth Q-switch is positioned in alignment with the third optical axisbetween the third highly reflective mirror and the third laser head. Thefourth, fifth and sixth Q-switches are horizontal Q-switches whichdivert the laser beam (radiation) horizontally.

A first control device which varies the timing, frequency and durationof control signals to the Q-switches is disclosed and claimed.

One example of the actuation of the Q-switches includes simultaneousmodulation thereof producing a short duration, high power radiationpulse in the laser output axis wherein the high power radiation pulse isthe sum of the power produced by the first, second, and third laserheads.

Another example of the actuation of the Q-switches includes modulationof the first, second, and third Q-switches sequentially without any timebetween pulses, and, results in a short duration, high power radiationpulse in the laser output axis, and each of the high power radiationpulses is substantially equal to the individual power of the first andsecond laser heads.

Another example of the actuation of the Q-switches includes modulationof the first, second, and third Q-switches sequentially but with timegaps therebetween, and, results in the provision of a series of shortduration temporally spaced apart, high power radiation pulses in thelaser output axis, each of the high power radiation pulse issubstantially equal to the individual power of the first and secondlaser heads.

A laser beam combining and power scaling method using a plurality oflaser heads arranged in parallel is disclosed and claimed. The methoduses a plurality of laser heads emitting radiation, a plurality ofrespective optical axes aligned with respective ones of the plurality oflaser heads, a plurality of first highly reflective mirrors residingperpendicularly with respect to respective ones of the plurality of theoptical axes and behind respective ones of the plurality of the laserheads, a plurality of second highly reflective mirrors residingperpendicularly with respect to respective ones of the plurality ofoptical axes, a plurality of beam splitters arranged at an incidenceangle with respect to respective ones of the optical axes and residingintermediate the respective ones of the plurality of laser heads and theplurality of second highly reflective mirrors, a common laser outputaxis, and a common output axis highly reflective mirror residingperpendicularly along the common laser output axis. The method includesthe steps of: directing, using the plurality of beam splitters,respective first portions of radiation emitted from the plurality oflaser heads along the common laser output axis; directing, using theplurality of beam splitters, respective second portions of the radiationemitted from the plurality of laser heads along the respective ones ofthe optical axes toward the plurality of second highly reflectivemirrors; reflecting, using the plurality of second highly reflectivemirrors residing perpendicularly with respect to respective ones of theplurality of optical axes, the respective plurality of second portionsof the radiation emitted from the plurality of laser heads along therespective ones of the optical axes toward the respective ones of thebeam splitters; directing, using the plurality of beam splitters,respective first portions of radiation emitted from the respective onesof the plurality of second highly reflective mirrors along the commonoutput axis toward the common output axis highly reflective mirrorresiding perpendicularly to the common output axis; directing, using theplurality of beam splitters, respective second portions of radiationemitted from the respective ones of the plurality of second highlyreflective mirrors through the beam splitter toward the respective onesof the plurality of laser heads; reflecting, using the common outputaxis mirror, the respective first portions of radiation received fromthe plurality of second highly reflective mirrors toward the pluralityof beam splitters; directing, using the plurality of the beam splitters,a plurality of first portions of radiation from the common output axishighly reflective mirror and along the common laser output axis; and,directing, using the plurality of the beam splitters, a plurality ofsecond portions of radiation from the common output axis highlyreflective mirror toward said plurality of second highly reflectivemirror.

Further, the process may include the following steps: controlling, usinga first control device, the timing, frequency and duration of theactuation of the Q-switches, and controlling, using a second controldevice, the timing, frequency and duration of the pumping of the laserheads; and, outputting, radiation from the laser heads along the commonlaser output axis. The process may include the following steps:controlling, using said first control device, the timing, frequency andduration of the actuation of the Q-switches which includes modulation ofthe Q-switches simultaneously, and further comprising the step of:providing a short duration, high power radiation pulse in the commonlaser output axis, the high power radiation pulse is the sum of thepower produced by the plurality of laser heads arranged in parallel.

Alternatively, the process may include the following steps: controlling,using the first control device, the timing, frequency and duration ofthe actuation of the Q-switches which includes modulation of theQ-switches sequentially without any time between pulses, and, furthercomprises the step of: providing a short duration, high power radiationpulse in the common laser output axis, the high power radiation pulse issubstantially equal to the individual power of each one of the pluralityof laser heads.

Alternatively, the process may include the following steps: controlling,using the first control device, the timing, frequency and duration ofthe actuation of the Q-switches which includes modulation of the firstand second Q-switches sequentially but with time gaps therebetween, and,further comprises the step of: providing a series of short durationtemporally spaced apart, high power radiation pulses in the common laseroutput axis, the high power radiation pulse are substantially equal tothe individual power of each one of the plurality of the laser heads.

It is an object of the invention to provide a multi-laser headconfiguration which has an adjustable output ranging from high energy,power stacked pulses at low frequency to low energy, sequenced pulses atvery high frequency or any permutation of these parameters in theaforesaid range.

It is an object of the invention to provide a current pulsed multi-laserhead configuration which has an adjustable output ranging from highenergy, power stacked pulses at low frequency to low energy sequencedpulses at very high frequency or any permutation of these parameters inthe aforesaid range wherein said laser heads are current pulse pumped soas to produce a pseudo continuous wave optical output.

It is an object of the invention to provide a continuously pumpedmulti-laser head configuration which is Q-switched and which may combinethe beams in a common output or which may provide a pulsed output.

It is an object of the invention to provide a multi-laser headconfiguration which has an adjustable output ranging from high energy,power stacked pulses at low frequency to low energy, sequenced pulses atvery high frequency or any permutation of these parameters in theaforesaid range wherein said laser heads are pumped with current pulses.

It is an object of the invention to provide a multi-laser headconfiguration which provides a short duration, high power radiationpulse in the common laser output axis, the high power radiation pulse isthe sum of the power produced by the plurality of laser heads arrangedin parallel.

It is an object of the invention to provide a multi-laser headconfiguration which provides a short duration, high power radiationpulse in the common laser output axis, the high power radiation pulse issubstantially equal to the individual power of each one of the pluralityof laser heads.

It is an object of the invention to provide a multi-laser headconfiguration which provides a series of short duration temporallyspaced apart, high power radiation pulses in the common laser outputaxis, the high power radiation pulses are substantially equal to theindividual power of each one of the plurality of the laser heads.

It is an object to provide a q-switched beam combining system which isused to narrow the optical pulse width at a given power level comparedto a single laser at the same given power level.

These and other objects will be better understood when reference is madeto the drawings and the description of the invention set forth below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of the prior art illustrating a laser head, ahighly reflective mirror, and a partially reflective mirror (outputcoupler).

FIG. 2 is a schematic of the prior art illustrating an intra-cavityoscillator which employs multiple laser heads (gain mediums) between ahighly reflective mirror and the partially reflective mirror (outputcoupler).

FIG. 3 is a schematic of the prior art illustrating a MasterOscillator/Power Amplifier (MOPA) system using a low power oscillatorwhich seeds a laser medium.

FIG. 4 is an illustration from prior art U.S. Pat. No. 5,307,369,entitled Laser Beam Combination System.

FIG. 5 is a schematic of an example of the invention illustrating laserbeam combining and power scaling using two laser heads, three highlyreflective mirrors, one 50% beam splitter, a laser output and verticaland horizontal Q-switches intermediate the two laser heads and theirrespective highly reflective mirrors.

FIG. 6 is a schematic of another example of the invention illustratinglaser beam combining and power scaling using three laser heads, threehighly reflective mirrors, one 50% beam splitter, a laser output, andvertical and horizontal Q-switches intermediate the three laser headsand their respective highly reflective mirrors.

FIG. 6A is a schematic of another example of the invention illustratinglaser beam combining and power scaling using three laser heads, threehighly reflective mirrors, one 50% beam splitter, and a laser output.

FIG. 6B is a plot of an optical power output versus current supplied tothe laser heads.

FIG. 7 is a schematic of another example of the invention illustratinglaser beam combining and power scaling using five laser heads, elevenhighly reflective mirrors, five 50% beam splitters, a laser output, andvertical and horizontal Q-switches intermediate the three laser headsand their respective highly reflective mirrors.

FIG. 7A is a schematic of another example of the invention illustratinglaser beam combining and power scaling using five laser heads, elevenhighly reflective mirrors, five 50% beam splitters, a laser output, andvertical and horizontal Q-switches intermediate the three laser headsand their respective highly reflective mirrors.

FIG. 8 is a Q-switch modulation timing chart for the three laser headconfiguration of FIGS. 6, 11 and 12.

FIG. 9 is another Q-switch modulation timing chart for the three laserhead configuration of FIGS. 6, 11 and 12.

FIG. 10 is another Q-switch modulation timing chart for the three laserhead configuration of FIGS. 6, 11 and 12.

FIG. 11 is a top view of the three laser head configuration of FIG. 6.

FIG. 12 is a perspective view of the three laser head configuration ofFIG. 6.

FIGS. 13 and 13A are a schematic illustration of one exemplary method oflaser beam combining and power scaling using first, second and thirdlaser heads having first, second and third optical axes.

FIGS. 14 and 14A are a schematic illustration of another exemplarymethod of a laser beam combining and power scaling using a plurality ofparallel laser heads arranged with a series of beam splitters and acommon output axis.

A better understanding of the invention will be had when reference ismade to the following description of the invention below.

DESCRIPTION OF THE INVENTION

Diode pumped solid state lasers have long lifetimes and enjoy highefficiencies. High electrical to optical efficiency leads to highoverall power efficiency of the laser.

Gain switched pulsed solid state lasers yield irregular pulses, namely,the pulses are irregular with respect to peak power, pulse width andrepetition frequency. Q-switching greatly increases the peak power andthe pulse widths have a short duration between several nanoseconds(10⁻⁹) and one microsecond (10⁻⁶) and can yield very high peakintensities. Q-switching is a method of laser generation where energy isstored in the laser medium and is suddenly released in a short pulse.The “Q” in “Q-switching” is the optical quality factor and is the ratioof the energy stored in the laser cavity to the energy lost per cycle.

When the active medium of the laser is pumped (energized), the beam pathis redirected resulting in a low Q factor and laser emission isprevented. Energy is stored in the active medium and the beam isreturned to proper alignment and most of the stored energy is releasedin a short pulse. A Q switch may be thought of as a shutter between theactive medium of the laser and the highly reflective mirror.

Laser machining is material removal accomplished by laser materialinteraction including, but not limited to, laser drilling, lasercutting, laser grooving, marking or scribing. Machining or materialremoval with lasers involves absorption of laser radiation by thematerial, transmission and redistribution of the energy within thematerial to be machined or altered, and removal of the material byevaporation and/or melting (and removal by ejection of vacuum). Laserparameters which affect machining include wavelength, pulse width andenergy, and beam intensity. Shortening of pulse length and increasingbeam intensity facilitates machining with lasers.

Shortening of pulse length and increase in beam intensity results inmuch thinner recast layers and heat affected zones (HAZ) and lessmicro-cracking or de-lamination of materials.

One example of the invention is set forth in FIG. 5 and schematicallydepicts a novel method of laser beam combining and power scaling usingthree highly reflective (HR) mirrors, one 50% beam splitter and at leasttwo Q switches. This new method produces multiple direct feedback pathsfor each laser head which keeps the power in each head at lowerindividual levels while also allowing the laser heads to be fired(pulsed) simultaneously or independently. Another example of theinvention is set forth in FIG. 6 and schematically includes combiningthe laser beams from three laser heads (resonators). Another example ofthe invention is set forth in FIG. 7 illustrating schematically five ormore laser beams combined together into a single beam. By controllingthe phasing of the laser pulses with respect to each other, a number offeatures can be maximized depending on the requirements and applicationof the laser. The pulses can be emitted synchronously, multiplying thepeak power by the number of heads in the configuration. The pulses canbe emitted one after the other, increasing the pulse energy and durationwithout increasing the peak power. The pulses can be emitted with equaltime between pulses, multiplying the repetition rate of the pulses. Thiscannot be done effectively using any of the current methods of laserpower scaling.

FIG. 5 is a schematic of one example of the invention illustrating laserbeam combining and power scaling device 500 using two laser heads 501,502, three highly reflective mirrors 503, 504, 505, one 50% beamsplitter 506, a laser output 507 and vertical 501A, 502A and horizontal501B, 502B Q-switches intermediate the two laser heads and theirrespective highly reflective mirrors. Q-switches create a large (energymagnitude expressed in Joules) pulse having a short pulse width. Bothlaser heads 501, 502 are diode pumped (not shown).

Referring to FIG. 5, laser head 501 (typically an NdYAG laserhead/medium) begins emission along the optical axes 508, 509 whenQ-switches 501A, 501B are energized by a high control signal asillustrated in FIG. 8, 9 or 10. Q-switches 501A, 501B are water cooledacousto-optical switches made by Gooch & Housego. Q-switch 501A is avertical Q-switch meaning that it deflects the radiation generated inthe laser head vertically and Q-switch 501B is a horizontal Q-switchmeaning that it deflects the radiation horizontally. Deflection of theradiation prevents lasing. Two Q-switches are employed to ensure thatlasing is held off. One Q-switch could be used but it would have to beoperated at higher power. Two switches are preferred as they may be runat lower power to ensure that lasing is held off. Laser head 502(typically an NdYAG laser head/medium) begins emission along opticalaxes 512, 513 when Q-switches 502A, 502B are energized by a high controlsignal as illustrated in FIG. 8, 9 or 10. Optical axis 511 is a thirdoptical axis and it is coincident with optical axes 508, 509.

When Q-switches 501A, 501B and 502A, 502B are actuated and permit lasingin respective laser heads 501, 502, radiation is emitted along firstoptical axis 509. First laser head 501 has a first optical axis 508,509. Preferably the first laser head is diode pumped. A first highlyreflective mirror 503 resides perpendicular to the first optical axis inalignment therewith behind the first laser head 501 and reflectsradiation when emitted from the first laser head 501.

A first Q-switch 501A in alignment with the first optical axis 508, 509is interposed between the first highly reflective mirror 503 and thefirst laser head 501. The second laser head 502 has a second opticalaxis 512, 513. The second laser head 502 is also diode pumped. A secondhighly reflective mirror 504 resides perpendicular to the second opticalaxis in alignment therewith behind the second laser head 502 andreflects radiation when emitted from the second laser head 502. A secondQ-switch 502A in alignment with the second optical axis is interposedbetween the second highly reflective mirror 504 and the second laserhead 502.

Still referring to FIG. 5, a third optical axis 511 is coincident withsaid first optical axis 508, 509. A third highly reflective mirror 505resides perpendicular to the third optical axis in alignment therewith.The second optical axis 512, 513 perpendicularly intersects the first508, 509 and the third 511 optical axes. A beam splitter 506 resides atthe intersection of the second optical axis and the first and thirdoptical axes. Laser output 507 has a laser output axis coincident withthe second optical axis 512, 513. The first laser head emits radiationalong the first axis 509 into and through the beam splitter 506. Thebeam splitter 506 directs a first portion of the radiation emitted fromthe first laser head along the third optical axis 511 and the beamsplitter 506 directs a second portion of the radiation emitted from thefirst laser head along the laser output axis 507 coincident with thesecond optical axis 512, 513.

The first portion of the radiation emitted from the first laser 501 headtravels along the third axis 511 and is reflected by the third highlyreflective mirror 505 toward the beam splitter. The beam splitter 506directs a first portion of the radiation emitted from the third highlyreflective mirror 505 into the first laser head along the first opticalaxis and the beam splitter directs a second portion of the radiationemitted from the third highly reflective mirror along the second opticalaxis into the second laser head.

The second laser head emits radiation along the second axis into andthrough the beam splitter 506. The beam splitter directs a first portionof the radiation emitted from the second laser head 502 along the laseroutput axis 507 and the beam splitter 506 directs a second portion ofthe radiation emitted from the second laser head 502 along the thirdoptical axis and into the third highly reflective mirror 505.

A first control device 520 varies the timing, frequency and duration ofthe control signals to the first 501A and second 502A Q-switches. Asecond control device 521 pumps first 501 and second 502 laser heads100% of the time when a diode pumped system is employed. Energy isapplied to the laser heads 501, 502, 100% of the time. The energy may bein the form of light emitting diodes in the case of the diode pumping orit may be in the form of incoherent light in the case of lamp pumping.The laser output 507 emits radiation from the first and second laserheads along the laser output axis.

The first 501A and second 502A Q-switches are vertical Q-switchesmeaning that they deflect the radiation upwardly (vertically) absent acontrol signal which defeats the deflection. The third Q-switch 501B isinterposed in alignment with the first optical axis 508 between thefirst Q-switch 501A and the first laser head 501. Third Q-switch 501B isa horizontal Q-switch meaning that the radiation is deflectedhorizontally absent a control signal which defeats the deflection. Afourth Q-switch 502B is interposed in alignment with the second opticalaxis between the second Q-switch 502A and the second laser head 502.Fourth Q-switch 502B is a horizontal Q-switch meaning that the radiationis deflected horizontally absent a control signal which defeats thedeflection.

As a first control example, a first control device 520 varies thetiming, frequency and duration of the actuation of the first and secondQ-switches by modulating the first and second Q-switches simultaneously.The control device 520 provides a short duration, high power radiationpulse in the laser output axis upon the application of control signalsto the first and second Q-switches as illustrated in FIG. 8. It is notnecessary to use both Q-switches 501A, 501B in the first optical axis508, nor is it necessary to use both Q-switches 502A, 502B in the secondoptical axis. Application of simultaneous pulses 801, 802 to Q-switches501A, 502A as set forth in FIG. 8 results in a high power radiationpulse which is the sum of the power produced by the first and secondlaser heads. FIGS. 8, 9 and 10 are examples of control algorithms whichmay be used and the user may employ vastly different control algorithmsdepending on the use of the laser.

When two Q-switches are used in each optical axis, they are alwayspulsed together as if they were one Q-switch.

As a second alternative control example, the first control device 520varies the timing, frequency and duration of the actuation of the firstand second Q-switches by modulating the first and second Q-switchessequentially without any time between pulses. The control device 520provides a short duration, high power radiation pulse in the laseroutput axis 507. Application of sequential pulses 901, 902 without anytime between them 901, 902 to Q-switches 501A, 502A as set forth in FIG.9 results in a high power radiation pulse which is substantially equalto the individual power of the first and second laser heads with thepulse being twice as long as the first example stated above wherein theQ switches are modulated simultaneously.

As a third alternative control example, the first control device 520varies the timing, frequency and duration of the actuation of the firstand second Q-switches by modulating the first and second Q-switchessequentially but with time gaps therebetween. The control device 520provides a series of short duration temporally spaced apart, high powerradiation pulses in the laser output axis. Application of sequentialpulses 1001, 1002 spaced apart by time gaps therebetween to Q-switches501A, 502A as set forth in FIG. 10 results in high power radiationpulses substantially equal to the individual power of the first andsecond laser heads spaced apart in time.

FIG. 6 is a schematic 600 of another example of the inventionillustrating a laser beam combining and power scaling using three laserheads 601, 602, 603, three highly reflective mirrors 603, 604, 618, one50% beam splitter 606, a laser output 607, and vertical 601A, 602A, 616Aand horizontal 601B, 602B, 616B Q-switches intermediate the three laserheads and their respective highly reflective mirrors 603, 604, 618.

FIG. 6A is a schematic 600A of another example of the inventionillustrating a laser beam combining and power scaling using three laserheads, three highly reflective mirrors, one 50% beam splitter, and alaser output without the Q-switches. The examples set forth in FIGS. 6Aand 7A may be used with different performance characteristics as theQ-switches provide short or narrow pulse widths and higher energy pulsesas compared to un-switched laser heads. The q-switched beam combiningsystem is used to narrow the optical pulse width at a given power levelcompared to a single laser at the same given power level.

In the examples of FIGS. 6A, and 7A which do not have the Q-switches, acurrent pulse may be applied to the laser heads.

Current pulse controlled lasers are limited to a duty cycle that dependson the specific system. In the example of FIG. 6A, reference numeral 622is used to denote current pulse control of the laser heads. The currentpulse control may be applied simultaneously to all the laser heads or itmay be applied sequentially with no time gaps between the sequentialfiring of the lasers. Or, the lasers may be fired sequentially with timegaps therebetween. Different controls may be applied to the laser headsillustrated in FIG. 6A. For instance, the laser heads may becontinuously energized and the output of FIG. 6A may be the sum of eachof the three laser heads, 601, 602 and 616. Each of the laser heads maybe operated, for instance, at fractional power enabling better controlof the system. If a single laser head is used at full power, increasedstress and heating on the optical components substantially lowers thequality of the laser beam creating lensing and optical waists that shiftthroughout the system and severely limits the power scaling achievable.

Another example of the laser beam combining and power scaling device isset forth in FIG. 6 and includes first 601, second 602 and third 616laser heads. First laser head 601 has a first optical axis 608, 609 andis preferably diode pumped. Alternatively, laser head 601 may be lamppumped. A first highly reflective mirror 603 resides perpendicular tothe first optical axis 608, 609 in alignment therewith behind the firstlaser head 601 reflecting radiation when emitted from the first laserhead. A first Q-switch 601A is interposed in alignment with the firstoptical axis 608, 609 between the first highly reflective mirror 603 andthe first laser head 601.

The second laser head 602 has a second optical axis 612, 613 and thelaser head is preferably diode pumped. A second highly reflective mirror604 resides perpendicular to the second optical axis 612, 613 inalignment therewith behind the second laser head reflecting radiationwhen emitted from the second laser head 602. A second Q-switch 602A isinterposed in alignment with the second optical axis between the secondhighly reflective mirror and the first laser head.

The third laser head 616 has a third optical axis 615, 617, and thethird laser head is diode pumped. A third highly reflective mirror 618resides perpendicular to the third optical axis in alignment therewithbehind the third laser head 616. A third Q-switch 616A in alignment withthe third optical axis 615, 617 is interposed between the third highlyreflective mirror and the third laser head. The first and third opticalaxes are coincident.

The second optical axis 612, 613 perpendicularly intersects the firstand third optical axes 608, 609; 615, 617. A beam splitter 606 residesat the intersection of the second optical axis 612, 613 and the firstand third optical axes. A laser output 607 has a laser output axiscoincident with the second optical axis. The first laser head 601 emitsradiation along the first optical axis 609 into and through the beamsplitter 606, the beam splitter directs a first portion of the radiationemitted from the first laser head 601 into the third laser head 616along the third optical axis 615. The beam splitter directs a secondportion of the radiation emitted from the first laser head along thelaser output axis 607 coincident with the second optical axis 613. Thethird laser head emits radiation along the third axis 615 into andthrough the beam splitter 606. The beam splitter directs a first portionof the radiation emitted from the third laser head 616 into the firstlaser head 601 along the first optical axis 609 where some of theradiation passes therethrough and is reflected from highly reflectivemirror 618. The beam splitter directs a second portion of the radiationemitted from the third laser head 616 along the second optical axis 613into the second laser head 602 where some of the radiation passestherethrough and is reflected from highly reflective mirror 603.

Still referring to FIG. 6, the second laser head 602 emits radiationalong the second axis into and through the beam splitter 606. The beamsplitter directs a first portion of the radiation emitted from thesecond laser head along the laser output axis 607. The beam splitterdirects a second portion of the radiation emitted from the second laserhead 602 along the third optical axis 615 and into the third laser head618 where some of the radiation passes therethrough and is reflectedfrom highly reflective mirror 618.

A first control device 620 varies the timing, frequency and duration ofcontrol signals to the first 601A, second 602A and third 616AQ-switches. A second control device 621 pumps the first 601, second 602and third 616 laser heads continuously, 100% of the time. The laseroutput 607 emits radiation from the first, second and third laser headsalong the laser output axis.

Still referring to FIG. 6, one operational example (the first examplepertaining to FIG. 6) of the first control device 620 is given whereinthe timing, frequency and duration of the actuation of the first, secondand third Q-switches is varied by modulating the first, second and thirdQ-switches simultaneously. The first control device provides a shortduration, high power radiation pulse in the laser output axis 607, and,the high power radiation pulse is the sum of the energy and powerproduced by the first 601, second 602 and third 616 laser heads.Referring to FIG. 8, a Q-switch modulation timing chart for the threelaser head configuration of FIGS. 6, 11 and 12 is disclosed wherein allthree laser heads are fired simultaneously. As stated above, FIG. 8 isapplicable to the operation of a two headed laser system and illustratesthe simultaneous occurrence of control impulses to the Q-switches topermit lasing. It will be noticed that FIG. 6 illustrates two sets ofQ-switches in the first 608, second 612 and third 617 optical axes.Q-switches 601A, 602A and 616A are vertical Q-switches meaning that theradiation beam is deflected vertically. These vertical acousto-opticalQ-switches alone are sufficient to hold off lasing although it ispreferred to include horizontal Q-switches 601B, 602B and 616B in eachof the optical axes as well to reduce the power supplied to eachQ-switch.

Still referring to FIG. 6, another operational example (the secondexample pertaining to FIG. 6) of the first control device is givenwherein the timing, frequency and duration of the actuation of the firstand second Q-switches is varied by modulating the first, second andthird Q-switches sequentially without any time between pulses. In thisexample as illustrated in FIG. 9, the control signals 901, 902, and 903defeat the Q-switches halting deflection of the radiation and providinga short duration, high power optical radiation pulse in the laser outputaxis. The short duration high power optical radiation pulse issubstantially equal to the individual energy and power of the first,second and third laser heads. The short duration high power pulse of theexample of FIG. 9 will be substantially three times as long as the firstoperational example.

Still referring to FIG. 6, another operational example (the thirdexample pertaining to FIG. 6) of the first control device is givenwherein the timing, frequency and duration of the actuation of thefirst, second, and third Q-switches is varied by modulating the first,second, and third Q-switches sequentially but with time gapstherebetween. The first control device provides a series of shortduration temporally spaced apart, high power radiation pulses in thelaser output axis. The high power optical radiation pulses aresubstantially equal in magnitude to the individual power of the first,second, and third laser heads. The control algorithm applied to a singleQ-switch in each optical axis, for instance Q-switches 601A, 602A and616A if they were used alone, is given in FIG. 10 by reference numerals1001, 1002 and 1003. These signals as represented by reference numerals1001, 1002, and 1003 are sequential and are spaced apart which willpermit the laser to essentially provide a stitched output if, forexample, the laser were to be used for this purpose.

Referring to FIG. 6A, if current pulse control is applied to the laserheads and if the frequency of the control impulses set forth in FIG. 10were to increase substantially, a pseudo continuous wave would beproduced by a sufficiently high repetition rate.

Q-switched performance of the example illustrated in FIG. 6, at 10 kHz,provides average power of 660 W (Watts), pulse energy of 66 mJ (milliJoules), nominal pulse width of 75 ns (nanoseconds) and peak pulse powerof approximately 880 kW (kilo watts).

Operation at 15 kHz yields average power of 700 W (Watts), pulse energyof 47 mJ (milli Joules), nominal pulse width of 100 ns (nanoseconds) andpeak pulse power of approximately 470 kW (kilo watts).

Operation at 20 kHz yields average power of 700 W (Watts), pulse energyof 35 mJ (milli Joules), nominal pulse width of 110 ns (nanoseconds) andpeak pulse power of approximately 318 kW (kilo watts).

FIG. 6 by way of example employs diode pumped NdYAG laser heads. Thirtysix (36) diodes rated at 40 W are used and are pumped at a wavelength of808 nm. Radio frequency power up to 100 W is applied to water cooledacousto optical Q switches. Q switch actuation (RF off time) istypically 8 μs. FIG. 6B illustrates graphically the total powerdelivered (laser output) simultaneously from the three head laser ofFIG. 6 plotted against the current supplied to the diodes. Testingperformed on the three headed laser at 1064 nm was performed having aspot size of 4 mm with a divergence of 11.4 mr (milli-radians).

FIG. 7 is a schematic 700 of another example of the inventionillustrating laser beam combining and power scaling using five laserheads 701, 702, 703, 704, 705, eleven highly reflective mirrors 701C,702C, 703C, 704C, 705C, 701B, 702B, 703B, 704B, 705B, 777, five 701S,702S, 703S, 704S, 705S, 50% beam splitters, a laser output 711, andvertical 701A, 702A, 703A, 704A, 705A and horizontal 701D, 702D, 703D,704D, 705D Q-switches intermediate the five laser heads and theirrespective highly reflective mirrors 701B, 702B, 703B, 704B, 705B.

FIG. 7A is a schematic 700A of another example of the inventionillustrating laser beam combining and power scaling using five laserheads, eleven highly reflective mirrors, five 50% beam splitters, alaser output. The example of FIG. 7A may be used with laser heads thatare pumped with current pulses as described in connection with FIG. 6Aabove.

A laser beam combining and power scaling device 700 is illustrated inFIG. 7 and comprises a plurality of laser heads arranged in parallel.The plurality of laser heads 701, 702, 703, 704, 705 emit radiation. Thelasers are preferably diode pumped and the preferred laser medium isNdYAG. A plurality of respective optical axes (712, 717—first opticalaxis; 713, 718—second optical axis; 714, 719—third optical axis; 715,720—fourth optical axis and 716, 721—fifth optical axis) are alignedwith respective ones of the plurality of laser heads. A plurality offirst highly reflective mirrors 701B, 702B, 703B, 704B, 705B residesperpendicularly with respective ones of the plurality of optical axes712, 713, 714, 715 and behind respective ones of the plurality of thelaser heads. A plurality of second highly reflective mirrors 701C, 702C,703C, 704C, 705C reside perpendicularly with respective ones of theplurality of optical axes 727, 728, 729, 730, 731 which are coincidentwith the optical axis of the laser heads.

Still referring to FIG. 7, a plurality of beam splitters 701S, 702S,703S, 704S, 705S are arranged at an incidence angle (typically 45°) withrespect to respective ones of the optical axes 717, 718, 719, 720, 721and reside intermediate the respective ones of the plurality of laserheads and the plurality of second highly reflective mirrors 701C, 702C,703C, 704C, 705C. A common laser output axis 711 comprises outputoptical axes 706, 707, 708, 709, 710, the output optical axes 707, 708,709 and 710 residing intermediate the beam splitters as illustrated inFIGS. 7 and 7A. The plurality of beam splitters direct respective firstportions of radiation emitted from the plurality of laser heads alongthe common laser output axis 706, 707, 708, 709, 710, 711. The pluralityof beam splitters 701S, 702S, 703S, 704S, 705S direct respective secondportions of the radiation emitted from the plurality of laser headsthrough the beam splitter along the respective ones 727, 728, 729, 730,731 of the optical axes toward the plurality of second highly reflectivemirrors 701C, 702C, 703C, 704C, 705C.

Still referring to FIG. 7, a common output axis highly reflective mirror777 resides perpendicularly along the common laser output axis 706, 707,708, 709, 710, 711. The plurality of second highly reflective mirrors701C, 702C, 703C, 704C, 705C reside perpendicularly with respect torespective ones of the plurality of optical axes 727, 728, 729, 730, 731reflecting the respective plurality of second portions of the radiationemitted from the plurality of laser heads 701, 702, 703, 704, 705 alongthe respective ones of the optical axes 727, 728, 729, 730, 731 towardthe respective ones of the beam splitters. The plurality of beamsplitters direct respective first portions of radiation emitted from therespective ones of the plurality of second highly reflective mirrors701C, 702C, 703C, 704C, 705C along the common output axis 706, 707, 708,709, 710, 711 toward the common output axis highly reflective mirror 777residing perpendicularly to the common output axis. The plurality ofbeam splitters direct respective second portions of radiation emittedfrom the respective ones of the plurality of second highly reflectivemirrors through the beam splitter toward the respective ones of theplurality of laser heads 701, 702, 703, 704, 705.

The common output axis mirror 777 reflects the respective first portionsof radiation received from the plurality of second highly reflectivemirrors toward the plurality of beam splitters 701S, 702S, 703S, 704S,705S. The plurality of beam splitters direct a plurality of firstportions of radiation from the common output axis highly reflectivemirror 777 through the beam splitters and along the common laser outputaxis 706, 707, 708, 709, 710, 711. As stated before, the beam splittersalso direct the first portions of radiation emitted from the pluralityof laser heads along the common laser output axis. Common output axis706, 707, 708, 709, 710, and 711 carries coherent light (radiation)which is emitted as indicated in FIG. 7. Further, the plurality of beamsplitters direct a plurality of second portions of radiation from thecommon output axis highly reflective mirror 777 toward the second highlyreflective mirrors 701C, 702C, 703C, 704C, 705C along said respectiveones of said optical axes 727, 728, 729, 730, 731.

Still referring to FIGS. 7 and 7A, a plurality of first acousto-opticalQ-switches 701A, 702A, 703A, 704A, 705A reside in respective ones of theplurality of the optical axes 712, 713, 714, 715, 716 between therespective ones of the laser heads 701, 702, 703, 704, 705 and theplurality of the first highly reflective mirrors 701B, 702B, 703B, 704B,705B. The first Q-switches are vertical Q-switches. A plurality ofsecond acousto-optical Q-switches 702D, 703D, 704D, 705D reside inrespective ones of the plurality of the optical axes between theplurality of first Q-switches and the respective ones of the laserheads. The plurality of second Q-switches are horizontal Q-switches. Afirst control device 740 varies the timing, frequency and duration ofcontrol signals to the first and second Q-switches. A second controldevice 741 applies constant direct current pumping of the laser heads.

Still referring to FIG. 7, one exemplary mode (first example) of thefirst control device varies the timing, frequency and duration of theactuation of the first and second Q-switches and modulates theQ-switches simultaneously for all of the laser heads. See, FIG. 8 asdescribed above in connection with the combination of 2 and 3 laserheads. In this example, a plurality of control signals are necessary,one for each laser head. Simultaneous application of control signals tothe Q-switch of all laser heads provides a short duration, high powerradiation pulse in the laser output axis. The high power radiation pulseis the sum of the energy power produced by all of the laser heads.

Still referring to FIG. 7, another exemplary mode (second example) ofthe first control device 740 varies the timing, frequency and durationof the actuation of the switches by modulating the Q-switchessequentially without any time between pulses. In this example, each ofthe laser heads fire in sequence beginning with 701, 702, 703 etc. Thiscontrol algorithm as expressed in FIG. 9 provides a short duration, highpower radiation pulse in the laser output axis. The magnitude of thehigh energy high power radiation pulse is substantially equal to theindividual energy and power of the individual laser heads. In otherwords, this example provides a lower magnitude pulse than the firstexample but the pulse would be longer by the number of laser heads.

Still referring to FIGS. 7 and 7A, another exemplary mode (thirdexample) of the first control device varies the timing, frequency andduration of the actuation of the Q-switches by modulating the Q-switchessequentially but with time gaps therebetween. This example provides aseries of short duration temporally spaced apart, high power radiationpulses in the laser output axis. The magnitude of the high powerradiation pulses are substantially equal in energy and power to theindividual energy and power of the individual laser heads.

In the example of FIG. 7A, reference numeral 742 denotes application andcontrol of a current pulse to the parallel laser heads 701, 702, 703,704 and 705. The current pulse control 742 may be applied simultaneouslyto all the parallel laser heads. Alternatively, current pulse controlmay be sequenced such that each of the laser heads are firedsequentially. Still alternatively, current pulse control may besequenced such that the current pulses are spaced apart in time.

FIG. 8 is a Q-switch modulation timing chart of the control device 620for the three laser head configuration of FIGS. 6, 11 and 12. Impulse801 to Q-switch occurs simultaneously with impulses 802 and 803 whichthen removes the deflection of laser beam. If two Q-switches are usedper laser head then the control impulses actuate both the vertical andhorizontal Q-switches simultaneously.

FIG. 9 is another Q-switch modulation timing chart of the control device620 for the three laser head configuration FIGS. 6, 11 and 12. Referencenumeral 901 is a sequential impulse to Q-switch removing deflection ofthe laser beam of the first laser head followed by sequential impulse902 to another Q-switch for removing deflection of the laser beam in thesecond laser head following impulse 901. Similarly, reference numeral903 is a sequential impulse to Q-switch removing deflection of the laserbeam for the third laser head.

FIG. 10 is another Q-switch modulation timing chart for the three laserhead configuration of FIGS. 6, 11 and 12. Reference numeral 1001 is asequential impulse to the first Q-switch removing deflection of thelaser beam followed by the spaced apart sequential impulse 1002 to theQ-switch removing deflection of laser beam for the second laser headfollowed by sequential impulse 1003 to the Q-switch removing deflectionof laser beam for the third laser head. Each of the sequenced impulsesis spaced apart in time.

If current pulsed control of the laser is employed and if the frequencyof operation and timing of the control channels on a laser head by laserhead basis is increased and accurately controlled by the control device622, then the operation of the laser results in a pseudo continuouswave.

FIG. 11 is a top view 1100 of the three laser head configuration of FIG.6. The laser heads, the Q-switches and the beam splitter as discussedabove are all illustrated in FIG. 11. FIG. 11 conserves space throughthe use of folding mirrors 1187, 1189. Apertures 1102, 1103, 1104, 1105,1106, 1107 are used as mode control devices producing higher qualitybeams. The mounting frame is denoted by reference numeral 1101 and theside of the frame is denoted by reference numeral 1111.

FIG. 12 is a perspective view 1200 of the three laser head configurationof FIG. 6. 1200-perspective view corresponding to the schematic view ofFIG. 6

One exemplary method as set forth in FIG. 13 utilizes: a first highlyreflective mirror residing perpendicular to the first optical axis inalignment therewith behind the first laser head reflecting radiationwhen emitted from the first laser head, a first Q-switch in alignmentwith the first optical axis interposed between the first highlyreflective mirror and the first laser head, a second highly reflectivemirror residing perpendicular to the second optical axis in alignmenttherewith behind the second laser head reflecting radiation when emittedfrom the second laser head; a second Q-switch in alignment with thesecond optical axis interposed between the second highly reflectivemirror and the second laser head, a third highly reflective mirrorresiding perpendicular to the third optical axis in alignment therewithbehind the third laser head, a third Q-switch in alignment with thethird optical axis interposed between the third highly reflective mirrorand the third laser head, the first and third optical axes beingcoincident, the second optical axis perpendicularly intersecting thefirst and the third optical axes, a beam splitter residing at theintersection of the second optical axis and the first and third opticalaxes, a laser output, the laser output having a laser output axis, thelaser output axis being coincident with the second optical axis, and, afirst control device.

The method as illustrated 1300 in FIG. 13 comprises the steps of:emitting radiation from the first laser head along the first axis intoand through the beam splitter-1301; directing, using the beam splitter,a first portion of the radiation emitted from the first laser head intothe third laser head along the third optical axis-1302; directing, usingthe beam splitter, a second portion of the radiation emitted from thefirst laser head along the laser output axis coincident with the secondoptical axis-1303; emitting radiation from the third laser head alongthe third axis into and through the beam splitter-1304; directing, usingthe beam splitter, a first portion of the radiation emitted from thethird laser head into the first laser head along the first opticalaxis-1305; directing, using the beam splitter, a second portion of theradiation emitted from the third laser head along the second opticalaxis into the second laser head emitting radiation from the second laserhead along the second axis into and through the beam splitter-1306;directing, using the beam splitter, a first portion of the radiationemitted from the second laser head along the laser output axis-1307;directing, using the beam splitter, a second portion of the radiationemitted from the second laser head along the third optical axis and intothe third laser head-1308; controlling, using a first control device,the timing, frequency and duration of the actuation of the first, secondand third Q-switches-1309; and, outputting, radiation from the first,second and third laser heads along the laser output axis-1311.

Alternatively, the method may include controlling, using the firstcontrol device, and varying the timing, frequency and duration of theactuation of the first, second and third Q-switches, includes modulatingthe first, second and third Q-switches simultaneously-1312. Thisprovides a short duration, high power radiation pulse in the laseroutput axis. The high power radiation pulse is the sum of the powerproduced by the first, second and third laser heads-1313.

Still alternatively, the method may include controlling, using the firstcontrol device, and varying the timing, frequency and duration of theactuation of the first, second and third Q-switches by modulating thefirst, second and third Q-switches sequentially without any time betweenpulses-1314. This provides a short duration, high power radiation pulsein the laser output axis, the high power radiation pulse issubstantially equal to the individual power of the first, second andthird laser heads-1315.

Still alternatively, the method may include controlling, using the firstcontrol device, and varying the timing, frequency and duration of theactuation of the first, second and third Q-switches by modulating thefirst, second and third Q-switches sequentially, but with time gapstherebetween-1316. This provides a series of short duration temporallyspaced apart, high power radiation pulses in the laser output axis. Eachof the high power radiation pulses is substantially equal to theindividual power of the first, second and third laser heads-1317.

Another exemplary laser beam combining and power scaling method asillustrated in FIG. 14 uses a plurality of laser heads arranged inparallel, the plurality of laser heads emitting radiation, a pluralityof respective optical axes aligned with respective ones of the pluralityof laser heads, a plurality of first highly reflective mirrors residingperpendicularly with respect to respective ones of the plurality of theoptical axes and behind respective ones of the plurality of the laserheads, a plurality of second highly reflective mirrors residingperpendicularly with respect to respective ones of the plurality ofoptical axes, a plurality of beam splitters arranged at an incidenceangle with respect to respective ones of the optical axes aligned withrespective ones of the plurality of laser heads, the plurality of beamsplitters reside intermediate the respective ones of the plurality oflaser heads and the plurality of second highly reflective mirrors, acommon laser output axis, and a common output axis highly reflectivemirror residing perpendicularly with respect to and along the commonlaser output axis.

The method as set forth in FIG. 14 comprises the steps of: directing,using the plurality of beam splitters, respective first portions ofradiation emitted from the plurality of laser heads along the commonlaser output axis 1401; directing, using the plurality of beamsplitters, respective second portions of the radiation emitted from theplurality of laser heads along the respective ones of the optical axesthrough the respective beam splitter and toward the plurality of secondhighly reflective mirrors-1402; reflecting, using the plurality ofsecond highly reflective mirrors residing perpendicularly with respectto respective ones of the plurality of optical axes, the respectiveplurality of second portions of the radiation emitted from the pluralityof laser heads along the respective ones of the optical axes toward therespective ones of the beam splitters-1403; directing, using theplurality of beam splitters, respective first portions of radiationemitted from the respective ones of the plurality of second highlyreflective mirrors along the common output axis toward the common outputaxis highly reflective mirror residing perpendicularly with respect tothe common output axis-1404; directing, using the plurality of beamsplitters, respective second portions of radiation emitted from therespective ones of the plurality of second highly reflective mirrorstoward the respective ones of the plurality of laser heads-1405;reflecting, using the common output axis mirror, the respective firstportions of radiation received from the plurality of second highlyreflective mirrors toward the plurality of beam splitters-1406;directing, using the plurality of the beam splitters, a plurality offirst portions of radiation from the common output axis highlyreflective mirror through the beams splitters along the common laseroutput axis-1407; directing, using the plurality of the beam splitters,a plurality of second portions of radiation from the common output axishighly reflective mirror toward the second highly reflectivemirrors-1408; controlling, using a first control device, the timing,frequency and duration of the actuation of the Q-switches-1409; and,outputting, radiation from the plurality of laser heads along the laseroutput axis-1411.

An exemplary control algorithm may be applied for the plurality of laserheads arranged in parallel. Specifically, the step of controlling, usingthe first control device, the timing, frequency and duration of theactuation of the Q-switches, includes modulation of the Q-switchessimultaneously-1412, thus providing a short duration, high powerradiation pulse in the laser output axis. The high power radiation pulseis the sum of the power produced by the plurality of laser headsarranged in parallel-1413.

Alternatively, another exemplary control algorithm, using the firstcontrol device, to vary the timing, frequency and duration of theactuation of the Q-switches, includes modulation of the Q-switchessequentially without any time between pulses-1414, thus providing ashort duration, high power radiation pulse in the laser output axis. Thehigh power radiation pulse is substantially equal to the individualpower of the ones of the plurality of the laser heads-1415.

Still alternatively, another exemplary control algorithm, using thefirst control device to vary the timing, frequency and duration of theactuation of the Q-switches, includes modulation of the Q-switchessequentially but with time gaps therebetween-1416, thus providing aseries of short duration temporally spaced apart, high power radiationpulse in the laser output axis. The high power radiation pulse issubstantially equal to the individual power of the ones of the pluralityof the laser heads-1417.

REFERENCE NUMERALS

-   10—prior art laser beam combination system-   20—first laser source-   22—second laser source-   30—fully reflective mirror-   32—fully reflective mirror-   36—fully reflective mirror-   40—beam splitter-   50—laser output-   51—line-   52—optical axis, line-   54—optical axis, line-   55—optical axis, line-   56—optical axis, line-   100—prior art standard laser system-   101—laser head/medium-   102—partially reflective output coupler-   103—highly reflective mirror-   104—optical axis/line-   105—optical axis/line-   106—laser output-   200—multiple intra-cavity oscillator-   201—second laser head/medium-   202—optical axis/line, combined output of first and second laser    head/medium-   203—partially reflective output coupler-   204—laser output-   300—master oscillator power amplifier (MOPA)-   301—second laser source-   302—partially reflective output coupler intermediate first laser    source and second laser source-   303—optical axis/line-   304—laser output-   400—prior art laser beam combination system-   500—continuous wave Q switched laser beam combination system-   501—first laser source-   501A—vertical acousto-optic Q switch-   501B—horizontal electro-optic Q switch-   502—second laser source-   502A—vertical acousto-optic Q switch-   502B—horizontal electro-optic Q switch-   503—highly reflective mirror-   504—highly reflective mirror-   505—highly reflective mirror-   506—beamsplitter, 50%-   507—laser output-   508—optical axis/line-   509—optical axis/line-   511—optical axis/line-   512—optical axis/line-   513—optical axis/line-   520—first control device-   521—second control device-   600—continuous wave Q-switched laser beam combination system using    three laser sources-   600A—current pulsed laser beam combination system without    Q-switching-   601—first laser source-   601A—vertical acousto-optic Q switch-   601B—horizontal electro-optic Q switch-   602—second laser source-   602A—vertical acousto-optic Q switch-   602B—horizontal acousto-optic Q switch-   603—highly reflective mirror-   604—highly reflective mirror-   606—beamsplitter, 50%-   607—laser output-   608—optical axis/line-   609—optical axis/line-   612—optical axis/line-   613—optical axis/line-   615—optical axis/line-   616—third laser source-   616A—vertical acousto-optic Q switch-   616B—horizontal acousto-optic Q switch-   617—optical axis/line-   618—highly reflective mirror-   620—first control device-   621—second control device for constant direct current application to    the laser heads-   622—current pulsing of the laser heads-   700—continuous wave Q-switched laser beam combination system    employing 4 or more laser sources-   700A—current pulsed laser beam combination system employing 4 or    more laser sources without Q-switching-   701—laser source-   701A, 702A, 703A, 704A, 705A—vertical acousto-optic Q switch-   701B—highly reflective mirror-   701C—highly reflective mirror-   701D, 702S, 703D, 704D, 705D—horizontal acousto-optic Q switch-   701S, 702S, 703S, 704S, 705S—beamsplitter, 50%-   702—laser source-   702B—highly reflective mirror-   702C—highly reflective mirror-   703—laser source-   703B—highly reflective mirror-   703C—highly reflective mirror-   704—laser source-   704B—highly reflective mirror-   704C—highly reflective mirror-   705—laser source-   705B—highly reflective mirror-   705C—highly reflective mirror-   706, 707, 708, 709, 710—output optical axis/line-   711—laser output-   712, 717—first optical axis/line-   713, 718—second optical axis/line-   714, 719—third optical axis/line-   715, 720—fourth optical axis/line-   716, 721—fifth optical axis/line-   727—optical axis/line-   728—optical axis/line-   729—optical axis/line-   730—optical axis/line-   731—optical axis/line-   740—first control device-   741—second control device for constant direct current application to    the laser heads-   742—current pulse control of the laser heads-   777—highly reflective mirror-   800—Q-switch modulation timing diagram for example disclosed in    FIGS. 6, 11 and 12-   801—impulse to Q-switch occurring simultaneously with impulse 802    and 803, removing deflection of laser beam-   802—impulse to Q-switch occurring simultaneously with impulse 801    and 803 removing deflection of laser beam-   803—impulse to Q-switch occurring simultaneously with impulse 801    and 802 removing deflection of laser beam-   900—Q-switch modulation timing diagram for example disclosed in    FIGS. 6, 11 and 12-   901—sequential impulse to Q-switch removing deflection of laser beam-   902—sequential impulse to Q-switch removing deflection of laser beam    after impulse 901-   903—sequential impulse to Q-switch removing deflection of laser beam    after impulse 902-   1000—Q-switch modulation timing diagram for example disclosed in    FIGS. 6, 11 and 12-   1001—sequential impulse to Q-switch removing deflection of laser    beam-   1002—sequential impulse to Q-switch removing deflection of laser    beam after impulse 1001-   1003—sequential impulse to Q-switch removing deflection of laser    beam after impulse 1002-   1100—top view corresponding to the schematic view of FIG. 6-   1101—mounting frame-   1102—aperture, mode control device producing higher quality beams,    blocks stray rays-   1103—aperture, mode control device producing higher quality beams,    blocks stray rays-   1104—aperture, mode control device producing higher quality beams,    blocks stray rays-   1105—aperture, mode control device producing higher quality beams,    blocks stray rays-   1106—aperture, mode control device producing higher quality beams,    blocks stray rays-   1107—aperture, mode control device producing higher quality beams,    blocks stray rays-   1111—side of mounting frame-   1187—steering/folding mirror-   1189—steering/folding mirror-   1200—perspective view corresponding to the schematic view of FIG. 6-   1300—laser beam combining and power scaling method using first,    second and third laser heads having first, second and third optical    axes-   1301—emitting radiation from the first laser head along the first    axis into and through the beam splitter-   1302—directing, using the beam splitter, a first portion of the    radiation emitted from the first laser head into the third laser    head along the third optical axis-   1303—directing, using the beam splitter, a second portion of the    radiation emitted from the first laser head along the laser output    axis coincident with the second optical axis-   1304—emitting radiation for the third laser head along the third    axis into and through the beam splitter-   1305—directing, using the beam splitter, a first portion of the    radiation emitted from the third laser head into the first laser    head along the first optical axis-   1306—directing, using the beam splitter, a second portion of the    radiation emitted from the third laser head along the second optical    axis into the second laser head emitting radiation from the second    laser head along the second axis into and through the beam splitter-   1307—directing, using the beam splitter, a first portion of the    radiation emitted from the second laser head along the laser output    axis-   1308—directing, using the beam splitter, a second portion of the    radiation emitted from the second laser head along the third optical    axis and into the third laser head-   1309—controlling, using a first control device, the timing,    frequency and duration of the actuation of the first, second and    third Q-switches-   1311—outputting, radiation from the first, second and third laser    heads along the laser output axis-   1312—controlling, using a first control device, the timing,    frequency and duration of the actuation of the first and second    Q-switches includes modulation of the first, second and third    Q-switches simultaneously-   1313—providing a short duration, high power radiation pulse in the    laser output axis, the high power radiation pulse is the sum of the    power produced by the first, second and third laser heads.-   1314—controlling, using a first control device, the timing,    frequency and duration of the actuation of the first, second and    third Q-switches includes modulation of the first and second    Q-switches sequentially without any time between pulses-   1315—providing a short duration, high power radiation pulse in the    laser output axis, the high power radiation pulse is substantially    equal to the individual power of the first and second laser heads-   1316—controlling, using a first control device, the timing,    frequency and duration of the actuation of the first and second    Q-switches includes modulation of the first, second and third    Q-switches sequentially but with time gaps therebetween-   1317—providing a series of short duration temporally spaced apart,    high power radiation pulse in the laser output axis, the high power    radiation pulse is substantially equal to the individual power of    the first, second and third laser heads.-   1400—a laser beam combining and power scaling method using a    plurality of laser heads arranged in parallel,-   1401—directing, using the plurality of beam splitters, respective    first portions of radiation emitted from the plurality of laser    heads along the common laser output axis-   1402—directing, using the plurality of beam splitters, respective    second portions of the radiation emitted from the plurality of laser    heads along the respective ones of the optical axes toward the    plurality of second highly reflective mirrors-   1403—reflecting, using the plurality of second highly reflective    mirrors residing perpendicularly with respective ones of the    plurality of optical axes, the respective plurality of second    portions of the radiation emitted from the plurality of laser heads    along the respective ones of the optical axes toward the respective    ones of the beam splitters-   1404—directing, using the plurality of beam splitters, respective    first portions of radiation emitted from the respective ones of the    plurality of second highly reflective mirrors along the common    output axis toward the common output axis highly reflective mirror    residing perpendicularly to the common output axis-   1405—directing, using the plurality of beam splitters, respective    second portions of radiation emitted from the respective ones of the    plurality of second highly reflective mirrors toward the respective    ones of the plurality of laser heads-   1406—reflecting, using the common output axis mirror, the respective    first portions of radiation received from the plurality of second    highly reflective mirrors toward the plurality of beam splitters-   1407—directing, using the plurality of the beam splitters, a    plurality of first portions of radiation from the common output axis    highly reflective mirror through the beam splitters along the common    laser output axis-   1408—directing, using the plurality of the beam splitters, a    plurality of second portions of radiation from the common output    axis highly reflective mirror toward the second highly reflective    mirrors-   1409—controlling, using a first control device, the timing,    frequency and duration of the actuation of the Q-switches-   1411—outputting, radiation from the laser heads along the laser    output axis-   1412—controlling, using the first control device, the timing,    frequency and duration of the actuation of the Q-switches via    modulation of the Q-switches simultaneously-   1413—providing a short duration, high power radiation pulse in the    laser output axis, the high power radiation pulse is the sum of the    power produced by the plurality of laser heads arranged in parallel-   1414—controlling, using the first control device, the timing,    frequency and duration of the actuation of the Q-switches via    modulation of the Q-switches sequentially without any time between    pulses-   1415—providing a short duration, high power radiation pulse in the    laser output axis, the high power radiation pulse is substantially    equal to the individual power of the ones of the plurality of the    laser heads-   1416—controlling, using the first control device, the timing,    frequency and duration of the actuation of the first and second    Q-switches via modulation of the Q-switches sequentially but with    time gaps therebetween-   1417—providing a series of short duration temporally spaced apart,    high power radiation pulse in the laser output axis, the high power    radiation pulse is substantially equal to the individual power of    the ones of the plurality of the laser heads.

Those skilled in the art will readily recognize that the invention hasbeen set forth by way of example and that changes may be made to theinvention without departing from the spirit and the scope of theappended claims.

1-18. (canceled)
 19. A laser beam combining and power scaling device,comprising: a plurality of laser heads arranged in parallel; saidplurality of laser heads emitting radiation; a plurality of respectiveoptical axes aligned with respective ones of said plurality of laserheads; a plurality of first highly reflective mirrors residingperpendicularly with respective ones of said plurality of said opticalaxes and behind respective ones of said plurality of said laser heads; aplurality of second highly reflective mirrors residing perpendicularlywith respective ones of said plurality of optical axes; a plurality ofbeam splitters arranged at an incidence angle with respect to respectiveones of said optical axes and residing intermediate said respective onesof said plurality of laser heads and said plurality of second highlyreflective mirrors; a common laser output axis; said plurality of beamsplitters directing respective first portions of radiation emitted fromsaid plurality of laser heads along said common laser output axis andsaid plurality of beam splitters directing respective second portions ofsaid radiation emitted from said plurality of laser heads along saidrespective ones of said optical axes toward said plurality of secondhighly reflective mirrors; a common output axis highly reflective mirrorresiding perpendicularly along said common laser output axis; saidplurality of second highly reflective mirrors residing perpendicularlywith respective ones of said plurality of optical axes reflecting saidrespective plurality of second portions of said radiation emitted fromsaid plurality of laser heads along said respective ones of said opticalaxes toward said respective ones of said beam splitters; said pluralityof beam splitters directing respective first portions of radiationemitted from said respective ones of said plurality of second highlyreflective mirrors along said common output axis toward said commonoutput axis highly reflective mirror residing perpendicularly to saidcommon output axis and said plurality of beam splitters directingrespective second portions of radiation emitted from said respectiveones of said plurality of second highly reflective mirrors toward saidrespective ones of said plurality of laser heads; said common outputaxis mirror reflecting said respective first portions of radiationreceived from said plurality of second highly reflective mirrors towardsaid plurality of beam splitters; and, and said plurality of said beamsplitters directing a plurality of first portions of radiation from saidcommon output axis highly reflective mirror and said first portions ofradiation emitted from said plurality of laser heads along said commonlaser output axis and said plurality of said beam splitters directing aplurality of second portions of radiation from said common output axishighly reflective mirror and said first portions of radiation emittedfrom said plurality of laser heads along said common laser output axis.20. A laser beam combining and power scaling device as claimed in claim19 wherein said laser heads are diode pumped.
 21. A laser beam combiningand power scaling device as claimed in claim 20, further comprising: aplurality of first Q-switches residing in respective ones of saidplurality of said optical axes between said respective ones of saidlaser heads and said plurality of said first highly reflective mirrors.22. A laser beam combining and power scaling device as claimed in claim21 wherein said plurality of first Q-switches are vertical Q-switches.23. A laser beam combining and power scaling device as claimed in claim20, further comprising: a plurality of second Q-switches residing inrespective ones of said plurality of said optical axes between saidplurality of first Q-switches and said respective ones of said laserheads.
 24. A laser beam combining and power scaling device as claimed inclaim 23 wherein said plurality of first Q-switches are verticalQ-switches and said plurality of second Q-switches are horizontalQ-switches.
 25. A laser beam combining and power scaling device asclaimed in claim 24, further comprising: a first control device, saidfirst control device varying the timing, frequency and duration ofcontrol signals to said first and second Q-switches.
 26. A laser beamcombining and power scaling device as claimed in claim 25, wherein saidfirst control device varies the timing, frequency and duration of theactuation of said first and second Q-switches and modulates said firstand second Q-switches simultaneously, providing a short duration, highpower radiation pulse in said laser output axis, said high powerradiation pulse is the sum of the power produced by said laser heads.27-49. (canceled)